me neither, i was literally screaming on the inside reading that ...again... here in the Class D forum of a DIY site. the perpetuation of that myth, how long since Class D was invented? is beyond frustrating
what about pulse width modulation sounds digital? even in a DAC this is in the analogue modulation stage.
Last edited:
What people seem to not understand is the basic principle on which the comparator work. It doesn't take a sample of the input signal. Instead it generates a comparator signal, usually a triangle wave and compare that to the input signal, thus deciding to turn on or off the output. Since the signal is analogue how long time the outputs are either on or off is completely analogue because it depends on the analogue input signal. The switching frequency is completely irrelevant in this respect because if it was a a-millionth of a hz the time the output are either on or off is still analogue.
PWM is a well defined process, frequencies well below PWM freq. are not altered at all during the conversion, there is solid mathematical proof.
A class D modulator is an analog computer, and particularly self oscillating modulators continuously compensate (by direct cancellation of error, no NFB) for changes in supply rails, without delays, in a PWM cycle by cycle basis, and PWM just comes from comparing a fraction of the integrated PWM at spk output to input signal. Open loop linearity is built-in, then NFB can be used. Simple+accurate=beauty.
A class D modulator is an analog computer, and particularly self oscillating modulators continuously compensate (by direct cancellation of error, no NFB) for changes in supply rails, without delays, in a PWM cycle by cycle basis, and PWM just comes from comparing a fraction of the integrated PWM at spk output to input signal. Open loop linearity is built-in, then NFB can be used. Simple+accurate=beauty.
There is no such thing as switching frequency in analog amplifier actually.
Analog amplifier purely controlled by original analog signal (for example music). It means that switches (transistors or tubes) can be in any state form completely off to fully on. Moreover they are never completely off or fully on but always on instead to some extent in Class A amp.
Class D is now workable without switching frequency.
Analog amplifier purely controlled by original analog signal (for example music). It means that switches (transistors or tubes) can be in any state form completely off to fully on. Moreover they are never completely off or fully on but always on instead to some extent in Class A amp.
Class D is now workable without switching frequency.
Nothing wrong with Class D in my book...
Budgie:
I agree. I have a Sure TK-2050 board. I think it's terrific. Bone stock. Would love to have your thoughts on modifications though.
Hmmm...to answer the loaded question: "What's wrong with class D?"
Uh....??????
1) Too inexpensive? (And therefore not easy to impress people with.)
2) Too small? (And therefore not easy to impress people with.)
3) No esoteric, highly unobtainable parts handcrafted by Tibetan monks on only the third full moon of a leap year? (And therefore not easy to impress people with.)
Need I continue?
I think the Shindo/McIntosh/Krell/Levinson set needs to quit eating caviar and thinking they have to spend the equivalent cost of a Hyundai to buy a decent amp or preamp. (What ARE they compensating for?) Or heck, for that matter, even interconnects. And get in the real world of audio. Make your own gear, or at least assemble it. Own it. Not simply whip out a credit card and then claim it's "better" because it costs 80 times what a class D amp does.
Class D is meat and potatoes baby -- it's macaroni and cheese goodness! It's home made pie -- not creme brule.
It's real. It's really good when done right (like everything else). I've had my expensive gear but I don't enjoy expensive audio gear as much as the stuff I build myself. Give me the cheap and cheerful (whoops, that's another forum!) stuff!
Mark
Budgie:
I agree. I have a Sure TK-2050 board. I think it's terrific. Bone stock. Would love to have your thoughts on modifications though.
Hmmm...to answer the loaded question: "What's wrong with class D?"
Uh....??????
1) Too inexpensive? (And therefore not easy to impress people with.)
2) Too small? (And therefore not easy to impress people with.)
3) No esoteric, highly unobtainable parts handcrafted by Tibetan monks on only the third full moon of a leap year? (And therefore not easy to impress people with.)
Need I continue?
I think the Shindo/McIntosh/Krell/Levinson set needs to quit eating caviar and thinking they have to spend the equivalent cost of a Hyundai to buy a decent amp or preamp. (What ARE they compensating for?) Or heck, for that matter, even interconnects. And get in the real world of audio. Make your own gear, or at least assemble it. Own it. Not simply whip out a credit card and then claim it's "better" because it costs 80 times what a class D amp does.
Class D is meat and potatoes baby -- it's macaroni and cheese goodness! It's home made pie -- not creme brule.
It's real. It's really good when done right (like everything else). I've had my expensive gear but I don't enjoy expensive audio gear as much as the stuff I build myself. Give me the cheap and cheerful (whoops, that's another forum!) stuff!
Mark
PLUS 3
A big +3 on that!
Mark
yawn.
how about this (tell me if you recognize the pattern).
1. listener A listens to class-A amp. it doesn't sound good. listener blames it on the room, accompanying equipment or cables.
2. listener A listens to class-D amp. it doesn't sound good. listener blames it on the amp. case closed.
A big +3 on that!
Mark
I suspect that is much the point - that the wealthy often purchase luxury goods as much for the fact that it shows they can afford to, as for the actual performance of the product. Just human nature, I suppose.
Ken,
Sort of the notion that two people need to live in a house with 25 bedrooms and 37 bathrooms because they can't find their way back to the first bedroom they started in! Yes that has a lot to do with the snob appeal of audiophile gear, they can buy it just because they have more money than brains sometimes! I am not saying this out of jealousy, I am just often left wondering how many ways can you figure out how to spend a few billion dollars when it keeps coming in, at what point are you ever satisfied and can enjoy the simple pleasures in life?
Sort of the notion that two people need to live in a house with 25 bedrooms and 37 bathrooms because they can't find their way back to the first bedroom they started in! Yes that has a lot to do with the snob appeal of audiophile gear, they can buy it just because they have more money than brains sometimes! I am not saying this out of jealousy, I am just often left wondering how many ways can you figure out how to spend a few billion dollars when it keeps coming in, at what point are you ever satisfied and can enjoy the simple pleasures in life?
Chapters 28-30 in Bob Cordell's book Audio Power Amplifiers does cover the design and implementation of class D very well. PWM does not have to use a triangle wave form to work, that is just one implementation of the design. Delta-Sigma is an alternative method of producing a class D amp and perhaps this is where the digital idea is coming from. They can be done in either the analog or the digital domain.
I mean analog PWM, where the switching transitions can happen at any time, not at the boundary of a clock cycle like in digital PWM from microcontrollers.
The timer for digital PWM is usually a counter, while the timer for analog PWM is usually the voltage across a capacitor (the result of integrating analog signals).
Last edited:
Yes, it seems that once one has enough wealth to acquire even the most extravagant of luxuries, simple greed becomes the motivation to accumulate wealth with little consideration of any other factor. The vast accumulation of wealth becomes a game of simple 'score keeping'. You know, where the one who dies holding the most wealth wins the 'game'.
Last edited:
It's fun to see capitalism failing just because one of its main features was not sustainable (it topped and popped): arbitrarily inflating the price of things, the dissociation between the price and the actual value (in terms of the substances and the energy expended to produce something).
You have not read my irony ... haha! sorry for this.
All debate, started by the recognition of a sound and what is made by the dynamics that distinguishes it from 'another. this to get to the fact that the PSU is responsible of fidelity to play a musical instrument.
This concept is hard to get into the minds of many who speak of high fidelity. even measures, fail in this, but for many years we have tried to solve this problem right on the high end hi-level in class AB with large capacitors.
This is a fact. or want to replace 150K-uF, with 15K-uF?
My position is uncomfortable, I do not want to force my smps. I think is right to divulgate the information, the measures and the concept have been developed for a long time to solve this problem.
---------------------------------------------------
Today just read an audio forum, to know that:
Class D is immune from the component on the vcc and voltage variations.
The class AB (for use audiophile) works just fine even with a smps for lamps.
amplifier with the same chip for television, is perfect for audiophiles.
Maybe there is something wrong?
regards
Last edited:
Very good point actually. For example regarding Mark Levinson
"The No.53 uses four interleaved class-I/IPT stages in a balanced bridge configuration, to produce an effective PWM switching frequency of 4MHz. This allows the No.53's signal bandwidth to be extended to 100kHz.
...
A six-layer printed-circuit board containing about 1500 parts incorporates the four isolated IPT modulator circuits, as well as the proprietary Link2 and MLNet system-control functions and the No.53's protection circuits. "
Ones can achieve 100kHz BW using OPA627+LM1875 that would be several hundred dollars DIY project. Or few tubes, few capacitors, few chokes and couple of audio trafos would set ones back for a couple grands while delivering 100kHz BW and providing decoupling of valuable part - speakers - by IDEAL protection circuit - OT
yeah I wasnt sure, irony is one of the harder things to make work without vocal tone, eye contact etc. but certainly nobody else did either so I thought I would get you to clarify regardless.
difficult for you, but not for me, the AP SMPS is something else. There, i've said it
indeed the TV chipamp is puzzling, but not new, I suppose tubes for many mundane purposes have become favored audio tubes, certainly some very cheap industrial dacs and transistors are framed as elite once they are obsolete.
difficult for you, but not for me, the AP SMPS is something else. There, i've said it
indeed the TV chipamp is puzzling, but not new, I suppose tubes for many mundane purposes have become favored audio tubes, certainly some very cheap industrial dacs and transistors are framed as elite once they are obsolete.
You have not read my irony ... haha! sorry for this.
All debate, started by the recognition of a sound and what is made by the dynamics that distinguishes it from 'another. this to get to the fact that the PSU is responsible of fidelity to play a musical instrument.
This concept is hard to get into the minds of many who speak of high fidelity. even measures, fail in this, but for many years we have tried to solve this problem right on the high end hi-level in class AB with large capacitors.
This is a fact. or want to replace 150K-uF, with 15K-uF?
My position is uncomfortable, I do not want to force my smps. I think is right to divulgate the information, the measures and the concept have been developed for a long time to solve this problem.
---------------------------------------------------
Today just read an audio forum, to know that:
Class D is immune from the component on the vcc and voltage variations.
The class AB (for use audiophile) works just fine even with a smps for lamps.
amplifier with the same chip for television, is perfect for audiophiles.
Maybe there is something wrong?
regards
I find that (generally and particularly in this thread) AP2's posts are hard to decode.
moreover, he uses a lot of hand-waving. the "this is difficult to explain" above. I like to think this is a technical forum with a relatively large average user "quality", not a gathering of easy to manipulate zombies.
stuff like "this is hard to explain" should not be accepted and responded with in a critical way. I've witnessed cases here where people seemed to be able to follow pretty complex explanations. I trust that there are such people reading this thread,
Class D is not immune from the component on the vcc and voltage variations.
The class AB (for use audiophile) doesn't work just fine even with a smps for lamps.
amplifier with the same chip for television, is not perfect for audiophiles.
and now I say... Maybe there is something wrong?
hope you get my point.
and...
I see this thing repeated from time to time, that the ear can't viewed as a frequency-domain analyzer and that there are some other phenomena at play. I once used to believe that, because some very vocal users here who also project a self-confident image kept repeating it. meanwhile I did a bit of homework. some people seem to believe that there are some mysterious time-domain phenomena that hide from the typical measurements. some even mention studies that show such phenomena. when asked for such studies, they answer that they can't do one's homework, that if one isn't aware of them then he's not up to the discussion level etc. some of them even sell devices that cure such mysterious phenomena.
I repeat, this is a technical forum. science doesn't work like that. I urge people to ask for hard facts and if such hard facts are not brought to light, they should try and draw some conclusion from it.
this is not politicians gathering votes, but nevertheless resembles that situation.
moreover, he uses a lot of hand-waving. the "this is difficult to explain" above. I like to think this is a technical forum with a relatively large average user "quality", not a gathering of easy to manipulate zombies.
stuff like "this is hard to explain" should not be accepted and responded with in a critical way. I've witnessed cases here where people seemed to be able to follow pretty complex explanations. I trust that there are such people reading this thread,
Today just read an audio forum (like this thread on this audio forum), to know that:
Class D is not immune from the component on the vcc and voltage variations.
The class AB (for use audiophile) doesn't work just fine even with a smps for lamps.
amplifier with the same chip for television, is not perfect for audiophiles.
and now I say... Maybe there is something wrong?
hope you get my point.
and...
I see this thing repeated from time to time, that the ear can't viewed as a frequency-domain analyzer and that there are some other phenomena at play. I once used to believe that, because some very vocal users here who also project a self-confident image kept repeating it. meanwhile I did a bit of homework. some people seem to believe that there are some mysterious time-domain phenomena that hide from the typical measurements. some even mention studies that show such phenomena. when asked for such studies, they answer that they can't do one's homework, that if one isn't aware of them then he's not up to the discussion level etc. some of them even sell devices that cure such mysterious phenomena.
I repeat, this is a technical forum. science doesn't work like that. I urge people to ask for hard facts and if such hard facts are not brought to light, they should try and draw some conclusion from it.
this is not politicians gathering votes, but nevertheless resembles that situation.
Last edited:
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.